1. Field of the Invention
This invention relates generally to a water bucket for helicopters and the like and, more particularly, the invention relates to water bucket systems having a computer controlled loading, partial drop control, and variable flow rates.
2. Description of the Prior Art
Not all wildfires can be fought from the ground. Due to rugged terrain and accessibility difficulties, aerial firefighting frequently becomes the most efficient and effective way of controlling wildfires. Aerial firefighting and protection of forests and related resources through controlling wildfires began in the late 1920's. Since the first 1200-pound sling by a Marine Corps Sikorsky helicopter in 1954, a small group of people in private industry and the U.S. Department of Agriculture have been developing various systems to effectively use helicopters for aerial firefighting.
Helicopter carried water buckets are well known for use in fighting forest fires. These buckets, at the simplest, may comprise of a rigid or flexible wall with a flapper valve at the bottom of the bucket. The pilot remotely activates the valve from the helicopter. This valve either works as a simple poppet type valve or is hinged in the center and a pneumatic cylinder or an electric actuator lifts the valve up off of the seal or pulls the two-hinged plates together allowing the bucket to drain. This requires great force due to the hydrostatic pressure at the bottom of the bucket.
The most commonly used water bucket uses an electric solenoid that releases the fabric underneath allowing the contents to drain. This design is limited in that once the solenoid is activated the entire contents are drained and splitting the load is impossible. The gated valve system with a load cell, providing a weight indication to the pilot, is becoming popular because of the ability to split the load and manage the weight lifted from the helicopter. Often times when dropping a load the pilot does not need to drop the entire load in one spot. The ability to make split drops saves trips back to the water source. In order to accomplish this the pilot must time the amount of water that comes out of the bucket and close the valve again before all the water is released.
Filling the bucket is a risky task for the pilot. The pilot must maintain a hover in adverse conditions while at the same time fill the bucket to a point that does not overload the aircraft. The current systems require the pilot to watch a load indicator connected to a load cell that measures the weight the helicopter is lifting. The pilot must manually open and close the bucket valve with a switch until the desired load is achieved. This is increased workload on the pilot at a time when the workload is already heightened. Other systems require the use of plugs, zippers, or cinch straps to manage weight.
During operations close to the ground, precise and rapid flight-control movements are required to avoid obstacles. The most common factor associated with obstacle-strike accidents is high workload. Thus, improvements made to decrease pilot workload such as the proposed invention should make the environment safer for the pilot.
Little data is gathered and categorized on accidents on the use of helicopters in the firefighting role operating under U.S. Federal Aviation Regulations Part 137 and 133. However, if reports of helicopters operating under U.S. Federal Aviation Regulations Part 135 are reviewed, some good correlations can be made. Data shows that pilot workload is the biggest cause of accidents related to human error. Reducing pilot workload will also allow the pilot to concentrate on the other factors associated with pilot error and should reduce risks in the other categories.